I’d say keep running 10Ks and half-marathons and get faster first for another season or two. It will benefit you more as a triathlete which is presumably your primary focus. When you can comfortably run a 1:20 13.1, then go for a sub 3 hr marathon, which is undesputedly respectable. No quotation marks needed.

I’m an injury prone runner, but every time I’ve bolted a marathon onto a 70.3 or IM season I’ve ended up injured. Best case scenario I’m left with a mediocre marathon result and spend the next couple months with green hair smelling like chlorine for so many swim and aqua jogging sessions.